off rhodamine based fluorescent probe for detection of Au and Pd in aqueous solutions

Sensors and Actuators B 246 (2017) 389–394

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Research Paper

On/off rhodamine based fluorescent probe for detection of Au and Pd in aqueous solutions A.Yu. Mironenko a,∗ , M.V. Tutov b , A.A. Sergeev c , Voznesenskiy c , S.Yu. Bratskaya a a Institute of Chemistry Far Eastern Branch of the Russian Academy of Sciences, 159, prosp.100-letiya Vladivostoka, Vladivostok 690022, Russia Vladivostok, Russia b Far Eastern Federal University, 8, Sukhanova St., Vladivostok 690950, Russia c Institute of Automation and Control Processes Far Eastern Branch of the Russian Academy of Sciences, 5, Radio street, Vladivostok 690041, Russia

a r t i c l e

i n f o

Article history: Received 26 September 2016 Received in revised form 13 February 2017 Accepted 15 February 2017 Available online 20 February 2017 Keywords: Rhodamine 6G On/off fluorescent chemosensor Au Pd detection

a b s t r a c t A water-soluble turn on/off rhodamine 6G based fluorescent probe for selective detection of Au and Pd ions in aqueous acidic solutions has been developed. The newly designed probe reacts with [AuCl4 ]− and [PdCl4 ]2− to generate a product with different optical properties. The probe undergoes a remarkable change in its absorption and emission spectrum upon addition of Au and Pd complexes that is associated with a discoloration and quenching of probe fluorescence. The probe exhibits near linear signal response and allows determination of Au and Pd content in aqueous solutions from 0.1 ␮M. © 2017 Elsevier B.V. All rights reserved.

1. INTRODUCTION In recent decades, the chemistry of gold as well as platinum group elements (Pt, Pd, Rh, Ir, Os) have become rapidly developing area of research due to its relevance to a number of issues in the field of materials science. A series of works have been published on various topics of Au, Pd, Pt chemistry, e.g. catalysis [1–4], nanostructures and patterned surfaces including surface-enhanced spectroscopic properties, such as Raman scattering [5,6] or fluorescence [7], as well developments in techniques such as surface plasmon resonance [8] and near-field scanning optical microscopy [9]. These elements also play an important role in medicine and biology as its derivatives are valuable for the treatment of a wide variety of diseases like tuberculosis [10,11] or cancer [12]. The determination of gold and platinum group elements in biological and industrial samples is an actual problem, and many recent papers have been devoted to it. Traditional analytical techniques used for detection of metals like atomic absorption spectrometry, plasma emission spectroscopy, solid-phase microextraction, X-ray fluorescence or neuron activation analysis allow quick detection with high sensitivity but need expensive instrumentation and complicated sample preparation procedure.

∗ Corresponding author. E-mail address: [email protected] (A.Yu. Mironenko). http://dx.doi.org/10.1016/j.snb.2017.02.092 0925-4005/© 2017 Elsevier B.V. All rights reserved.

Recent years have seen a great progress in development of luminescent and colorimetric probes and for analyzing cations [13–16], neutral analytes [17] or important organic substances [18] in solutions and gases [19]. Compared to common analytical techniques, optical probes offer the advantage of using simple instrumentation and feasibility to build miniaturized and highly sensitive fiber- or planar optical waveguide based sensor systems [20,21]. The rhodamines have been widely used to construct off-on fluorescence probes. Modification of carboxylic acid group of carboxyphenyl ring through a secondary amide bond formation will result in the synthesis of a rhodamine lactam non-fluorescent dye that becomes fluorescent only in acidic conditions or in the presence of metal cations (Fig. 1) [22]. Due to the fact that the equilibrium lactam-amide is strongly dependent on pH level and solvent system, the majority of chemosensors for recognition of heavy and transition metal ions, for example, Hg2+ , Fe2+ , Co2+ , Cr3+ or Cd2+ , are applicable only in solutions with neutral pH level [23–26]. A few rhodamine based probes for fluorescent detection of gold ions in organic solvents or aqueous-organic media have been reported [27–29] and all of them require the use of organic cosolvent or neutral pH media. Widespread use of gold precursors in science and industry thus needs efficient and convenient detection methods to evaluate and monitor its concentration in various solutions. The aim of the work was to develop fluorescent probe with

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Fig. 1. The scheme of modification of rhodamine amino group and spirolactam ring-opening process of modificated derivative.

Fig. 2. Scheme of synthesis.

sulfur-containing ligands and test it on applicability for detection of gold in acidic water conditions. 2. Experimental 2.1. Reagents and apparatus DMSO (Sigma-Aldrich, 99%), hexane (Sigma-Aldrich, 95%) were purified by stirring over calcium hydride for 24 h followed by distillation. Acetone (Sigma-Aldrich, 99.5%) was purified by stirring over anhydrous calcium sulfate for 24 h followed by distillation. Rodamine 6G (Sigma-Aldrich, 99%), cysteamine hydrochloride (Fluka, 97%), Na2 CO3 , acetic anhydride (Sigma-Aldrich, 98%), Silica gel (5/40 ␮m) were used as received. All other chemicals were of analytical grade. IR spectra of the compounds in the range 400–4000 cm−1 were recorded using a Perkin Elmer Spectrum 100BX-II spectrometer in KBr pellets. NMR spectra were recorded on the Bruker Avance 400 with the frequency of proton resonance 400 MHz using CDCl3 and DMSO-d6 as solvents. Mass spectra were received using LC-ESI/MS system Shimadzu LCMS-2010. Fluorescence spectra were recorded using Shimadzu RF-6000 spectrofluorophotometer. The pH values of the solutions were measured using Sartorius Professional Meter PP-50. The concentrations of metal ions were determined by atomic absorption spectroscopy, using a Solar AA 6a spectrometer.

118.05, 110.00, 105.48, 96.59, 65.22, 38.77, 39.38, 38.23, 38.37, 34.90, 29.27, 29.44, 29.70, 22.81, 23.11, 16.75, 14.73 (Fig. 2S); FT-IR (KBr, ␯, cm−1 ): 3375, 3076, 2966, 2928, 2868, 1676, 1620, 1518, 1470, 1421, 1382, 1352, 1271, 1217, 1157 (Fig. 3S); ESI-MS (m/z, +␯e mode) 591.2 (Probe 1 + H)+ (Fig. 4s), calc. for C36 H46 N4 O3 S4 is 591.24 (Fig. 2). 3. Results and discussion 3.1. Effect of cations on Probe 1 luminescent properties First of all, the fluorescent turn-on properties of Probe 1 were tested over a range of pH values from 2 to 7 (Fig. 3, black circles) and the change of fluorescence intensity upon interaction with different cations (Fig. 4). As it was expected, the fluorescent intensity at 554 nm of Probe 1 is pH dependent and increase with decrease of pH value from 7 to 2, what is caused by the typical spirolactam ring-open reaction in acidic condition. We have assumed that the enhance of luminescence will be observed at neutral pH level after addition of specific cation and formation of luminescent complex, however the reverse process has been revealed. Thus, it was shown that addition of [AuCl4 ]− and [PdCl2 ]2− complex anions leads to quenching of Probe 1 luminescent signal. Additions of other metal ions including Co2+ , Ca2+ , Mn2+ , Cu2+ , Zn2+ , Ba2+ , Hg2+ , Ni2+ , Pb2+ ,

2.2. Synthesis and characterization of Probe 1

0,8

FL intensity, a.u.

N-acetylcysteamine was prepared by the following procedure [30]. A 50 mg (1.11·10−4 mol) Rodamine 6G, 132 mg (1.11·10−3 mol) of N-acetylcysteamine and 118 mg (1.11·10−3 mol) of Na2 CO3 were dissolved in 5 ml of DMSO. The mixture was heated under stirring at 120 ◦ C for 2 h. Then cooled to room temperature and dissolved in 200 ml of distilled water. A colored precipitate was filtered, washed with water (3 × 50 ml) and dried at 80 ◦ C under reduced pressure. A crude product was purified by flash column chromatography on a silica gel with acetone/hexane (v/v = 1/1) as the eluent to afford the product as a light pink powder (38.8 mg, 47.97%). 1 H NMR (400 MHz, DMSO-d6, ppm, ␦): 8.00-7.97 (t, 1H), 7.817.71 (m, 1H), 7.55-7.49 (m, 2H), 7.02-6.98 (m, 1H), 6.26 (s, 2H), 6.07 (s, 2H), 5.10 (br.t, 2H), 3.47-3.39 (m, 2H+H2 O), 3.27-3.23 (t, 2H), 3.17-3.09 (m, 6H), 2.30-2.23 (m, 2H), 1.86 (s, 6H), 1.78 (s, 3H), 1.22-1.18 (t, 6H) (Fig. 1S); 13 C NMR (100 MHz, CDCl3, ppm, ␦): 170.98, 167.90, 153.49, 151.78, 147.58, 132.80, 130.93, 128.25, 128.29, 123.93, 122.74,

Probe_1 Probe_1 + [AuCl4]-

1,0

0,6

0,4

0,2

0,0 2

3

4

5

6

7

pH Fig. 3. Dependence of Probe 1 and Probe 1-Au3+ complex fluorescence intensity on pH level.

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3.2. Effect of pH and response time The fluorescence spectra response of Probe 1 (10−5 M) in the absence and presence of [AuCl4 ]− (10−4 M) in different pH values were examined to find a suitable pH in which Probe 1 can be used efficiently. As shown in Fig. 2, significant luminescence quenching is observed in the pH range from 2 to 4, therefore, probe 1 may allow Au and Pd ions detection in acidic conditions and sodium acetate buffer (pH 3.3) was used through the experiments. The reaction time on the present system was investigated by monitoring the fluorescent emission intensity of Probe 1 (10−5 M) reacting with Au3+ and Pd2+ (10−5 M) at an excitation wavelength of 534 nm. As it is seen from Fig. 5 the response of Probe 1 is rather slow. After the addition of Au3+ or Pd2+ , the fluorescent intensity of Probe 1 was quenched to a constant value after ∼3–4 h interaction. So, at all further experiments the samples were kept overnight before recording of fluorescence spectra. Fig. 4. Fluorescent response of Probe 1 (10−5 M) to various metal ions (10−4 M).

4

1,0x10

Probe_1 + Pd2+ Probe_1 + Au3+

3

FL intensity, a.u.

8,0x10

3

6,0x10

3

4,0x10

3.3. Sensing properties A fluorescence titration experiments were carried out to reveal sensing nature of Probe 1 (10−5 M). Upon progressive addition of [AuCl4 ]− and [PdCl2 ]2− ions, a gradual decrement in the fluorescence at 554 nm was observed (Fig. 6). To implement Hill plot (Fig. 7), the fluorescence response of Probe 1 toward analyte was normalized as R = 1−Ii /Imax , where Imax – luminescent intensity of Probe 1 without analyte, Ii - luminescent intensity of Probe 1 with analyte. Probe 1 have shown a linear relationship between the emission intensity and the analyte concentration in the range of 10−7 –10−5 M Au (Fig. 7a insert) and 10−7 –5·10−6 Pd (Fig. 7b insert). On the basis of the signal-to-noise ratio of three, the detection limit of Probe 1 for Au was estimated to be 2·10−7 M or 0.02 Eq, for Pd 1·10−7 or 0.01 Eq.

3

2,0x10

3.4. Binding of Probe 1 with Au3+ and Pd2+

0,0 0

60

120

180

240

Time, min Fig. 5. Probe 1 (10−5 M) response kinetics toward Au3+ and Pd2+ (10−5 M) cations.

Al3+ , Fe3+ , Tb3+ , Eu3+ and Cr3+ have not caused significant changes in fluorescent intensity under the same conditions. These results further indicated that developed chemosensor had a high sensitivity and selectivity for Au and Pd ions in aqueous media.

a)

There are several methods for spectrophotometric determination of gold in solutions based on formation of ion associates of [AuCl4 ]− with a number of reagents. The reaction of [AuCl4 ]− with the cationic form of Rhodamine B gives a violet ion pair complex with absorbance maximum at 565 nm [31]. To establish the nature of binding of Probe 1 with [AuCl4 ]− we have observed characteristics peaks of anion at 225 and 310 nm (Fig. 8). Decrease of these peaks indicates the dissociation of [AuCl4 ]− and formation of new complex. The binding ratio and apparent association constant (Ka) of Au3+ and Pd2+ complexes were determined by the titration experiment (Fig. 9a, 9b). Ka of Probe 1/Au3+ and Probe 1/Pd2+ were determined

b)

7x105

7x104 6x104

5x105 4x10

Fl. intensity, a.u.

FL intensity, a.u.

6x105

5

3x105 2x10

5

5x104 4x104 3x104 2x104

1x105

1x104

0

0

540

560

580

600 λ, nm

620

640

540

560

580

600

620

640

λ, nm

Fig. 6. Fluorescent spectrum changes of Probe 1 (10−5 M) at increasing concentration of metal ions (␭ex = 534 nm, ␭em = 554).

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Fig. 7. Dependence of response signal on concentration of Au3+ ions (b) and Pd2+ ions (c) (␭ex = 534 nm, ␭em = 554).

3.5. Influence of Cl− concentration and cross-sensitivity

4,0 3,5

after mixing after 2 hours

[AuCl4]-

3,0

Abs.

2,5 2,0 1,5 Probe_1 1,0 0,5 0,0 200

300

400

500

600

700

λ, nm Fig. 8. UV–vis spectra of the solution containing 3·10−4 M [AuCl4 ]− and 10−4 M Probe 1 before and after formation of complex Probe 1/Au3+ .

to be 1.08·108 and 8.35·108 respectively. Job’s plots (Fig. 9), which exhibited an inflection at 0.75 M and 0.5 M fraction of Au3+ and Pd2+ , indicated that a 3:1 complex was formed between Au3+ and Probe 1 and a 1:1 complex between Pd2+ and Probe 1.

Further, we studied the influence of Cl− anion concentration on the dissociation of the Probe 1-metal complex and on the value of signal change. Fluorescent spectroscopic experiments were carried out with Probe 1-Au complex in the absence and presence of sodium chloride salt. As shown in Fig. 10, the noticeable changes were not observed after the addition of 0.3 M of NaCl to the solution containing 10−4 Probe 1–Au complex. Because the sensing mechanism utilizes the chemical reaction of complex formation, the sensor response can be influenced by the presence of other metal cations. We have investigated the signal interference to Co2+ , Ca2+ , Mn2+ , Cu2+ , Zn2+ , Ba2+ , Hg2+ , Ni2+ , Pb2+ , Al3+ , Fe3+ , Tb3+ , Eu3+ and Cr3+ on sensor response. Fig. 11 presents the response values of Probe 1 (10−5 M) on the presence of 10−5 M of [AuCl4 ]− with 10−4 M of tested cation. According to the obtained data (Fig. 11), it can be concluded that no significant signal interference occurs. 4. Conclusions In summary, we report a new rhodamine-derived chemosensor (Probe 1) for the selective determination of Au3+ and Pd2+ in acidic aqueous media. The sensing properties of Probe 1 were examined by visual inspection and fluorescence spectroscopy. The probe showed highly selective and sensitive colorimetric and “on–off” fluorescence response toward Au3+ and Pd2+ over a wide range of metal ions. Upon addition of metal ions, the solution of Probe 1

Fig. 9. Job’s plots for the binding of Au3+ (a) and Pd2+ (b).

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1,0 w/o NaCl 0.3M NaCl

FL intensity, a.u.

0,8

0,6

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0,0 540

560

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λ, nm Fig. 10. Fluorescent spectra of 10−4 M Probe 1-Au complex solutions with different concentration of NaCl.

Fig. 11. Cross sensitivity diagram of Probde 1.

shows significant color change from pink to colorless and shows remarkable ‘on–off’ fluorescence. Acknowledgment Financial support from Russian Foundation of Basic Research (Project No 16-33-60100 mol a dk) is gratefully acknowledged. The studies of fluorescent response were supported by the Russian President’s grant MK-8089.2016.2. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.snb.2017.02.092. References [1] X. Chen, H. Zhu, R. Groarke, Catalysis by supported gold nanoparticles, Ref. Modul. Mater. Sci. Mater. Eng. (2016) 1–11. [2] L.A. Pretzer, K.N. Heck, S.S. Kim, Y.L. Fang, Z. Zhao, N. Guo, et al., Improving gold catalysis of nitroarene reduction with surface Pd, Catal. Today 264 (2016) 31–36.

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[3] Z. Xu, Y. Liu, F. Ren, F. Yang, D. Ma, Development of functional nanostructures and their applications in catalysis and solar cells, Coord. Chem. Rev. 320–321 (2016) 153–180. [4] T. Yao, Q. Zuo, H. Wang, J. Wu, B. Xin, F. Cui, et al., A simple way to prepare Pd/Fe3 O4 /polypyrrole hollow capsules and their applications in catalysis, J. Colloid Interface Sci. 450 (2015) 366–373. [5] J. Chen, S. Pang, L. He, S.R. Nugen, Highly sensitive and selective detection of nitrite ions using Fe3 O4 @SiO2 /Au magnetic nanoparticles by surface-enhanced Raman spectroscopy, Biosens. Bioelectron. 85 (2016) 726–733. [6] L. Jin, G. She, J. Li, J. Xia, X. Wang, L. Mu, et al., A facile fabrication of Ag–Au–Ag nanostructures with nanogaps for intensified surface-enhanced Raman scattering, Appl. Surf. Sci. 389 (2016) 67–72. [7] H. Li, J. Kang, J. Yang, B. Wu, Fabrication of Aunanoparticle@mSiO2 @Y2 O3 :Eu nanocomposites with enhanced fluorescence, J. Alloys Compd. 673 (2016) 283–288. [8] X. Liu, Y. Yang, L. Mao, Z. Li, C. Zhou, X. Liu, et al., SPR quantitative analysis of direct detection of atrazine traces on Au-nanoparticles: nanoparticles size effect, Sens. Actuators B 218 (2015) 1–7. [9] H.K. Park, Y.T. Lim, J.K. Kim, H.G. Park, B.H. Chung, Nanoscopic observation of a gold nanoparticle-conjugated protein using near-field scanning optical microscopy, Ultramicroscopy 108 (2008) 1115–1119. [10] C. Da Silva, J.G. Ferreira, A.E. Mauro, R.C.G. Frem, R.H.A. Santos, P.B. Da Silva, et al., Synthesis and antimycobacterial activity of new pyrazolate-bridged dinuclear complexes of the type [Pd(␮-L)(N3)(PPh3)]2 (PPh3 = triphenylphosphine; L = pyrazolates), Inorg. Chem. Commun. 48 (2014) 153–155. [11] C. da Silva, L.B. Ribeiro, C.C. Furuno, G.A. da Cunha, R.F.F. de Souza, A.V.G. Netto, et al., Pyrazolyl Pd(II) complexes containing triphenylphosphine: synthesis and antimycobacterial activity, Polyhedron 100 (2015) 10–16. [12] C.W. Fong, Platinum anti-cancer drugs: free radical mechanism of Pt-DNA adduct formation and anti-neoplastic effect, Free Radic. Biol. Med. 95 (2016) 216–229. [13] A.Yu. Mironenko, A.A. Sergeev, A.E. Nazirov, A.A. Leonov, S.Yu. Bratskaya, S.S. Voznesenskiy, Sensitive coatings for luminescence detection of Cu(II) in solutions, Solid State Phenom 245 (2015) 243–246. [14] H. Wang, L. Yang, W. Zhang, Y. Zhou, B. Zhao, X. Li, A colorimetric probe for copper(II) ion based on 4-amino-1,8-naphthalimide, Inorganica Chim. Acta. 381 (2012) 111–116. [15] J. Jeong, B.A. Rao, Y.-A. Son, Dual sensing performance of a rhodamine-derived scaffold for the determination of Cu2+ and Ce4+ in aqueous media, Sens. Actuators B 220 (2015) 1254–1265. [16] D.P. Singh, R. Dwivedi, A.K. Singh, B. Koch, P. Singh, V.P. Singh, A dihydrazone based “turn–on” fluorescent probe for selective determination of Al3+ ions in aqueous ethanol, Sens. Actuators B 238 (2017) 128–137. [17] Y. Kurauchi, M. Nagase, N. Egashira, K. Ohga, Response of a fiber-optic sensor with a chitosan/poly(vinyl alcohol) cladding to organic solvents in water, Anal. Sci. 13 (1997) 987–990. [18] X. Wu, H. Shu, B. Zhou, Y. Geng, X. Bao, J. Zhu, Design and synthesis of a new rhodamine B-based fluorescent probe for selective detection of glutathione and its application for live cell imaging, Sens. Actuators B 237 (2016) 431–442. [19] N. Kumar, V. Bhalla, M. Kumar, Recent developments of fluorescent probes for the detection of gasotransmitters (NO, CO and H2S), Coord. Chem. Rev. 257 (2013) 2335–2347. [20] A.Yu. Mironenko, A.A. Sergeev, A.E. Nazirov, E.B. Modin, S.S. Voznesenskiy, S.Yu. Bratskaya, H2 S optical waveguide gas sensors based on chitosan/Au and chitosan/Ag nanocomposites, Sens. Actuators B 225 (2016) 348–353. [21] A.Yu. Mironenko, A.A. Sergeev, S.S. Voznesenskiy, D.V. Marinin, S.Yu. Bratskaya, pH-indicators doped polysaccharide LbL coatings for hazardous gases optical sensing, Carbohydr. Polym. 92 (2013) 769–774. [22] M. Beija, C. Afonso, J. Martinho, Synthesis and applications of rhodamine derivatives as fluorescent probes, Chem. Soc. Rev. 38 (2009) 2410–2433. [23] J. Hu, Z. Hu, Y. Cui, X. Zhang, H.-W. Gao, K. Uvdal, A rhodamine-based fluorescent probe for Hg2+ and its application for biological visualization, Sens. Actuators B 203 (2014) 452–458. [24] S. Ji, X. Meng, W. Ye, Y. Feng, H. Sheng, Y. Cai, et al., A rhodamine-based “turn-on” fluorescent probe for Fe3+ in aqueous solution, Dalt. Trans. 43 (2014) 1583–1588. [25] P. Xie, F. Guo, Y. Xiao, Q. Jin, D. Yao, Z. Huang, A fluorescent chemosensor based on rhodamine for Cr3+ in red spectral region in aqueous solutions and living cells, J. Lumin. 140 (2013) 45–50. [26] P. Ma, B. Zhang, Q. Diao, L. Li, Y. Sun, X. Wang, D. Song, A water-soluble fluorescent probe for ClO− and Cd2+ under physiological pH and its applications in living cells imaging, Sens. Actuators B 233 (2016) 639–645. [27] L. Yuan, W. Lin, Y. Yang, J. Song, A fast-responsive fluorescent probe for detection of gold ions in water and synthetic products, Chem. Commun. (Camb). 47 (2011) 4703–4705. [28] J.L. Wang, W.Y. Lin, L. Yuan, J.Z. Song, W.S. Gao, Development of a reversible fluorescent gold sensor with high selectivity, Chem. Commun. 47 (2011) 12506–12508. [29] N. Niamsa, C. Kaewtong, W. Srinonmuang, B. Wanno, B. Pulpoka, T. Tuntulani, Hybrid organic–inorganic nanomaterial sensors for selective detection of Au3+ using rhodamine-based modified polyacrylic acid (PAA)-coated FeNPs, Polym. Chem. 4 (2013) 3039–3046.

394

A.Yu. Mironenko et al. / Sensors and Actuators B 246 (2017) 389–394

[30] A.J. Hughes, A. Keatinge-Clay, Enzymatic extender unit generation for in vitro polyketide synthase reactions: structural and functional showcasing of Streptomyces coelicolor MatB, Chem. Biol. 18 (2011) 165–176. [31] J. Tournebize, A. Sapin-Minet, R. Schneider, A. Boudier, P. Maincent, P. Leroy, Simple spectrophotocolorimetric method for quantitative determination of gold in nanoparticles, Talanta 83 (2011) 1780–1783.

Biographies A.Yu. Mironenko received Ph.D. degree in Institute of Chemistry Far Eastern Branch of Russian Academy of Sciences in 2014. His research interests are concerned with development of nanocomposite materials for optical applications. M.V. Tutov received Ph.D. degree in the Far-Eastern National University in 2015. Now working as a senior lecturer at the Department of Inorganic and elementorganic

chemistry of School of Natural Sciences FEFU. His research interests lie in a field of synthesis of new organosilicon functional polymers and dendrimers. A.A. Sergeev received Ph.D. degree in Institute of Automation and Control Processes Far Eastern Branch of Russian Academy of Sciences. His research interests are laser physics and integrated optics. Dr. S.S. Voznesenskiy received Dr. of Sciences (Biophysics) in Institute of Automation and Control Processes Far Eastern Branch of Russian Academy of Sciences in 2011. His research areas are optical sensing system, photonics crystal, and biomedical sensing areas. Dr. S.Yu. Bratskaya received her Diploma in Chemistry (M.S.) from the Far East State University and Dr. of Sciences (Physical Chemistry) degree from Institute of Chemistry Far Eastern Branch of Russian Academy of Sciences. Her areas of expertise are colloidal and surface chemistry with focus on fabrication of biopolymer functional coatings.